Anodization apparatus and anodization method

ABSTRACT

According to one embodiment, an anodization apparatus includes: a first process tank configured to perform an anodization process on a substrate; a holder configured to hold the substrate; and a first electrolyte supply system configured to supply a first electrolyte to the first process tank. The holder immerses the substrate in the first electrolyte in a state where the substrate is inclined with respect to a liquid level of the first electrolyte. The anodization process is executed in a state where the substrate is inclined with respect to the liquid level of the first electrolyte.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-019756, filed Feb. 10, 2021, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an anodization apparatus and an anodization method.

BACKGROUND

A technology of forming porous film on a substrate surface by anodization is known.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram of an anodization apparatus according to a first embodiment.

FIG. 2 is a diagram describing a rotated state of an anode holder in the anodization apparatus according to the first embodiment.

FIG. 3 is a flowchart of an anodization process in the anodization apparatus according to the first embodiment.

FIG. 4 is an overall configuration diagram of an anodization process system according to a second embodiment.

DETAILED DESCRIPTION

In general, according to one embodiment, an anodization apparatus includes: a first process tank configured to perform an anodization process on a substrate; a holder configured to hold the substrate; and a first electrolyte supply system configured to supply a first electrolyte to the first process tank. The holder immerses the substrate in the first electrolyte in a state where the substrate is inclined with respect to a liquid level of the first electrolyte. The anodization process is executed in a state where the substrate is inclined with respect to the liquid level of the first electrolyte.

Hereinafter, embodiments will be described with reference to the drawings. In the following description, structural elements having approximately the same function and configuration will be assigned the same reference symbol, and a repeat description will be given only where necessary. The embodiments to be described below are given as an example of an apparatus or a method for embodying the technical idea of the embodiments, and are not intended to limit the material, shape, structure, arrangement, etc. of components to those described below.

1. First Embodiment

An anodization apparatus according to a first embodiment will be described. In the present embodiment, an anodization apparatus that forms a silicon porous layer (for example, a porous Si layer) on a surface of a semiconductor substrate (hereinafter simply referred to as a “substrate”) will be described.

1.1 Basic Configuration of Anodization Apparatus

An example of a basic configuration of an anodization apparatus will be described with reference to FIG. 1. FIG. 1 is a configuration diagram of the anodization apparatus.

As shown in FIG. 1, an anodization apparatus 1 includes an anodization tank 10, an anode holder 11, a first electrolyte supply system 13, a concentration adjustment unit 14, a temperature adjustment unit 15, a second electrolyte supply system 16, a current source 17, and a control circuit 18.

The anodization tank 10 is a process tank used for anodization. The anodization tank 10 has a cylindrical shape, for example. The inner diameter of the anodization tank 10 is larger than the outer diameter of the anode holder 11. An insulating material is used for the anodization tank 10.

A pipe 201 and a pipe 202 are coupled to the anodization tank 10. The pipe 201 is used when supplying a first electrolyte from the first electrolyte supply system 13 to the anodization tank 10. The first electrolyte is a liquid used for an anodization process, and is an electrolyte containing at least hydrogen fluoride (HF). The pipe 202 is used when refluxing the first electrolyte from the anodization tank 10 to the first electrolyte supply system 13.

A cathode tank 101, a cathode 102, a filter 103, and a diffusion plate 104 are provided in the anodization tank 10.

When the first electrolyte is supplied to the anodization tank 10, the cathode tank 101 functions as a shower head casing in combination with the diffusion plate 104. The cathode tank 101 has a cylindrical shape, for example. The inner diameter of the cathode tank 101 is, for example, preferably equal to or larger than the outer diameter of a substrate 110 which is a target of anodization. An insulating material is used for the cathode tank 101. The bottom surface of the cathode tank 101 contacts the bottom surface inside the anodization tank 10. An opened portion of the upper end of the cathode tank 101 is inclined with respect to the bottom surface of the cathode tank 101 and thereby the diffusion plate 104 may be attached in an inclined manner with respect to a liquid level of the first electrolyte.

The cathode 102 functions as a cathode in the anodization process. The cathode 102 has a disk shape, for example. The cathode 102 contacts the bottom surface inside the cathode tank 101. The diameter of the cathode 102 is, for example, the same as the inner diameter of the cathode tank 101. The cathode 102 is made of conductive materials, and uses materials with low reactivity to the first electrolyte (with almost no dissolution in the first electrolyte). The cathode 102 may be a conductive material using, for example, carbon, diamond, Pt, or Au as a coating material. Furthermore, the coating material may be a glass-like fiber carbon, a diamond coat silicon or the like.

The filter 103 is provided above the cathode 102 in the cathode tank 101. In other words, the filter 103 is provided between the cathode 102 and the diffusion plate 104. In the anodization process, the filter 103 removes particles generated at the cathode 102. For example, even when a material that is hard to dissolve in the first electrolyte is used for the electrode material of the cathode 102, the electrode may undergo oxidization due to aging, etc., and generate particles. When the particles are generated, they may inhibit porous silicon from being forming in the anodization process. The size of the particles that may be removed by the filter 103 can be designed as appropriate. For example, as the filter 103, a filter that can remove particles with a particle diameter of 0.01 μm or more may be used.

In the present embodiment, one end of the pipe 201 is provided in a manner penetrating the bottom part of the anodization tank 10, the bottom part of the cathode tank 101, the cathode 102, and the filter 103, and the first electrolyte is supplied to the cathode tank 101 from the first electrolyte supply system 13.

The diffusion plate 104 is fixed to the opened portion of the upper end of the cathode tank 101 in a state of being inclined at angle θ (0°<θ<90°) with respect to the liquid level of the first electrolyte (or the bottom surfaces of the anodization tank 10 and the cathode tank 101). The diffusion plate 104 is provided with a plurality of holes for diffusing the first electrolyte. The diameter and arrangement of the holes may be designed as appropriate. After being diffused by the diffusion plate 104, the first electrolyte is supplied to the surface of the substrate 110 (the surface to be anodized) that is fixed to the anode holder 11. Hereinafter, a surface on which a porous layer is to be formed by anodization will be referred to as a front surface of the substrate 110, and a surface on which the porous layer is not to be formed will be referred to as a back surface of the substrate 110. The diffusion plate 104 is made of insulating materials, and uses materials with low reactivity to the first electrolyte (with almost no dissolution in the first electrolyte). As the diffusion plate 104, for example, it is preferable to use poly-tetra-fluoro-ethylene (PTFE), polyvinyl chloride, or materials on which antistatic measures have been taken.

The anode holder 11 functions as a holder for fixing the substrate 110. When performing anodization, the anode holder is immersed in the first electrolyte with the substrate 110.

The anode holder 11 includes a base 111, an anode 112, and a wafer clamp 113.

The base 111 has a disk shape, for example. The diameter of the base 111 is, for example, equal to or larger than the diameter of the substrate 110. An insulating material, for example, is used for the base 111.

The anode 112 functions as an anode in the anodization process. The anode 112 has a disk shape, for example. The diameter of the anode 112 is, for example, the same as the diameter of the base 111. The anode 112 contacts the bottom surface of the base 111 in a state where at least a part of the anode holder 11 and the substrate 110 are immersed in the first electrolyte inside the anodization tank 10. The anode 112 is made of conductive materials, and uses materials with low reactivity to a second electrolyte described later. The anode 112 may be a conductive material using, for example, carbon, diamond, Pt, or Au as a coating material. Furthermore, the coating material may be a glass-like fiber carbon, a diamond coat silicon or the like.

The wafer clamp 113 has a cylindrical shape, for example. On the side surface of the wafer clamp 113, for example, a groove for fixing the base 111 and the anode 112 is provided. Furthermore, the lower end of the wafer clamp 113 is provided with an edge seal for fixing the substrate 110. The outer diameter of the wafer clamp 113 is larger than the outer diameters of the substrate 110, the base 111, and the anode 112. In a state where at least a part of the anode holder 11 and the substrate 110 are immersed in the first electrolyte inside the anodization tank 10, the edge seal of the wafer clamp 113 is in contact with the entire surface of the outer circumference of the substrate 110 and fixes the substrate 110 in a manner such that the front surface of the substrate 110 faces downwards (on the diffusion plate 104 side).

The wafer clamp 113 fixes the substrate 110 and the anode 112 in a manner such that the back surface of the substrate 110 (the surface not to be anodized) is not in contact with the anode 112, and the substrate 110 and the anode 112 are in parallel. The wafer clamp 113 is made of insulating materials, and uses materials with low reactivity to the first electrolyte and the second electrolyte (with almost no dissolution in the electrolytes). As the diffusion plate 104, for example, it is preferable to use PTFE, polyvinyl chloride, or materials on which antistatic measures have been taken.

In the present embodiment, in order to bring the substrate 110 and the anode 112 into conduction, the second electrolyte having conductivity is supplied from the second electrolyte supply system 16 to a space defined by the back surface of the substrate 110, the anode 112, and the wafer clamp 113. More specifically, the anode holder 11 is coupled to a pipe 203 for supplying the second electrolyte from the second electrolyte supply system 16 to the anode holder 11, and a pipe 204 for refluxing the second electrolyte to the second electrolyte supply system 16. The pipes 203 and 204 are provided in a manner penetrating the base 111 and the anode 112, and the second electrolyte is supplied to the above-described space from the second electrolyte supply system 16. In other words, the second electrolyte fills the space between the anode 112 and the substrate 110.

In the anodization process, in some cases, the second electrolyte subjected to electrolysis may cause gas to be generated in the above-described space. In such a case, a path may be provided in the anode holder 11 to discharge the gas.

It should be noted that, in the present example, although a case of bringing the substrate 110 and the anode 112 into conduction by supplying the second electrolyte to the space between the substrate 110 and the anode 112 is described, it is not limited thereto. For example, the back surface of the substrate 110 may be brought into contact with the anode 112. On the surface of the anode 112 with which the substrate 110 is to be in contact, a low resistive layer which is injected with a high dopant concentration, or a metal that can perform an ohmic contact with respect to the substrate 110, may also be provided.

An anode holder driving mechanism 12 is fixed on the center portion of the upper surface of the base 111. The base 111 is made rotatable by the anode holder driving mechanism 12 in a state where at least a part of the anode holder 11 and the substrate 110 are immersed in the first electrolyte inside the anodization tank 10. In other words, the anode holder driving mechanism 12 is fixed to the center portion of a surface of the base 111 facing a surface on which the anode 112 is provided, in which manner the base 111 is rotatable. The anode holder driving mechanism 12 has a mechanism for immersing at least a part of the base 111 in the anodization tank 10 in a state where the base 111 is inclined by angle θ, and rotating the base 111 in such a state. Therefore, in the present embodiment, at least a part of the anode holder 11 and the substrate 110 are immersed in the first electrolyte in a state where they are inclined by angle θ with respect to the liquid level of the first electrolyte of the anodization tank 10. The anode holder driving mechanism 12 inclines the substrate 110 and the anode 112 by angle θ, thereby allowing the substrate 110, the anode 112, and the diffusion plate 104 to be provided in a parallel state in the anodization process. By arranging the substrate 110, the anode 112, and the diffusion plate 104 in a parallel state, the in-plane uniformity of the current density relating to the substrate 110 improves. It should be noted that the anode 112 and the diffusion plate 104 may or may not be provided in a parallel state. Even in a case where the anode 112 and the cathode 102 are not provided in a parallel state, and the distance between the anode 112 and the cathode 102 is uneven, it is possible to improve the in-plane uniformity of the current density relating to the substrate 110 by arranging the substrate 110 and the diffusion plate 104 in a parallel state. Furthermore, the in-plane uniformity of the current density relating to the substrate 110 improves by inclining the diffusion plate 104 in the same direction as the substrate 110 with respect to the bottom surface of the anodization tank 10 or the liquid level of the first electrolyte.

A specific example of a rotated state of the anode holder 11 will be described with reference to FIG. 2. FIG. 2 shows a cross-section of the anode holder 11 and an upper surface of the base 111 in the rotated state.

As shown in FIG. 2, the anode holder driving mechanism 12 rotates the base 111 inclined by angle θ about the anode holder driving mechanism 12 serving as a rotational axis. By inclining the base 111 by angle θ the substrate 110 and the anode 112 become inclined by angle θ. For example, the anode holder driving mechanism 12 rotates the base 111 and the substrate 110 in the range of 10 to 100 rpm.

The first electrolyte supply system 13 will now be described with reference to FIG. 1. The first electrolyte supply system 13 supplies the first electrolyte to the anodization tank 10. The first electrolyte is a liquid to be used for the anodization process. As the first electrolyte, for example, a liquid containing a hydrogen fluoride (HF) is used. More specifically, for example, a mixed liquid of an HF solution and ethanol or isopropyl alcohol (IPA) is used for the first electrolyte. The first electrolyte supply system 13 of the present embodiment has a function of circulating the first electrolyte between the anodization tank 10 and the first electrolyte supply system 13. The first electrolyte supply system 13 supplies the first electrolyte for which concentration is adjusted to the cathode tank 101 via the pipe 201, and recovers the first electrolyte from the anodization tank 10 via the pipe 202. The first electrolyte supply system 13 does not necessarily have a function for circulating the first electrolyte. In such a case, the pipe 202 is omitted, and the first electrolyte in the anodization tank 10 is processed as a waste liquid.

The first electrolyte supply system 13 includes an ingredient supply unit 131, a mixing tank 132, and a pump 133.

The ingredient supply unit 131 supplies ingredients of the first electrolyte to the mixing tank 132 based on the control of the control circuit 18 and the concentration adjustment unit 14. Ingredients may be, for example, an HF solution, alcohol, and DIW (deionized water). As for the ingredients, materials other than liquids may be used.

The mixing tank 132 mixes ingredients supplied from the ingredient supply unit 131 with the first electrolyte recovered from the anodization tank 10 using the pipe 202, and produces a first electrolyte that can be used for the anodization process.

The pump 133 compresses and transfers the first electrolyte produced in the mixing tank 132 to the cathode tank 101 via the pipe 201. The pump 133 may also be used when transferring the first electrolyte in the mixing tank 132 to a waste liquid line (not shown). Furthermore, another pump may be provided for the waste liquid line.

The concentration adjustment unit 14 adjusts the concentration of the first electrolyte. The concentration adjustment unit 14 includes a concentration sensor 141. The concentration sensor 141 is coupled to the pipe 201. The concentration sensor 141 measures an ion concentration of the first electrolyte supplied from the first electrolyte supply system 13. The concentration adjustment unit 14 feeds back the measurement result of the concentration sensor 141 to the ingredient supply unit 131, and adjusts the amount of ingredients to be supplied in the ingredient supply unit 131. This allows the concentration of the first electrolyte supplied to the anodization tank 10 to be maintained at a certain level, and H₂SiF₆, etc., which is a by-product of the anodization process, to be filtered. The concentration adjustment unit 14 may be provided in the first electrolyte supply system 13.

The temperature adjustment unit 15 adjusts the temperature of the first electrolyte. The temperature adjustment unit 15 includes a temperature sensor 151. The temperature sensor 151 is coupled to the pipe 201, and monitors the temperature of the first electrolyte. For example, the temperature adjustment unit 15 includes a tiller or a heater, and cools or heats the first electrolyte in accordance with the result of the temperature monitor. Thus, the temperature adjustment unit 15 maintains the temperature of the first electrolyte in the anodization tank 10 at a certain level. The temperature adjustment unit 15 may be provided in the first electrolyte supply system 13.

The second electrolyte supply system 16 supplies the second electrolyte to the anode holder 11. The second electrolyte is used to bring the anode 112 and the substrate 110 into conduction. As the second electrolyte, a liquid at least containing a conductive material is used. More specifically, for example, the conductive material may include at least one of HF, HCl, NaCl, KCl, KOH, H₃PO₄, or TMAH (Tetra-Methyl-Ammonium-Hydroxide).

The second electrolyte supply system 16 of the present embodiment has a function of circulating the second electrolyte between the anode holder 11 and a mixing tank 162. The second electrolyte supply system 16 supplies the second electrolyte for which concentration is adjusted to the anode holder 11 via the pipe 203, and recovers the second electrolyte from the anode holder 11 via the pipe 204. The second electrolyte supply system 16 does not necessarily have a function for circulating the second electrolyte. In such a case, the pipe 204 is omitted, and the second electrolyte in the anode holder 11 is processed as a waste liquid.

The second electrolyte supply system 16 includes an ingredient supply unit 161, the mixing tank 162, and a pump 163.

The ingredient supply unit 161 supplies ingredients of the second electrolyte to the mixing tank 162 based on the control of the control circuit 18. The ingredients may be solutions such as HF, HCl, NaCl, KCl, KOH, H₃PO₄, and TMAH, and DIW (deionized water), etc. As for the ingredients, materials other than liquids may be used.

The mixing tank 162 mixes ingredients supplied from the ingredient supply unit 161 with the second electrolyte recovered from the anode holder 11 using the pipe 204, and produces a second electrolyte.

The pump 163 compresses and transfers the second electrolyte produced in the mixing tank 162 to the anode holder 11 via the pipe 203. The pump 163 may also be used when transferring the second electrolyte in the mixing tank 162 to a waste liquid line. Furthermore, another pump may be provided for the waste liquid line. The pump 163 may set the supply pressure of the second electrolyte higher than the supply pressure of the first electrolyte so that the entire surface of the outer circumference of the substrate 110 is pressed against the edge seal of the wafer clamp 113.

The current source 17 is coupled to the anode 112 and the cathode 102, and supplies a desired amount of current to the anode 112 when the anodization is performed.

The control circuit 18 controls the entire anodization apparatus 1. More specifically, the control circuit 18 controls the anode holder driving mechanism 12, the first electrolyte supply system 13, the concentration adjustment unit 14, the temperature adjustment unit 15, the second electrolyte supply system 16, and the current source 17.

1.2 Flow of Anodization Process

An example of the flow of the anodization process will be described with reference to FIG. 3. FIG. 3 is a flowchart of the anodization.

As shown in FIG. 3, first, the first electrolyte supply system 13 starts supplying the first electrolyte to the anodization tank 10 (step S1).

The substrate 110 is set on the anode holder 11 in a manner such that the back surface of the substrate 110 (the surface not to be anodized) faces the anode 112 (step S2).

The second electrolyte supply system 16 starts supplying the second electrolyte to the anode holder 11 (step S3). This allows the space between the substrate 110 and the anode 112 to be filled by the second electrolyte.

The anode holder driving mechanism 12 inclines the anode holder 11 (the base 111), in which the substrate 110 is set and to which the second electrolyte is supplied, by angle θ. The anode holder driving mechanism 12 immerses at least a part of the anode holder 11 and the substrate 110 in the first electrolyte in the anodization tank 10 in a state where the anode holder 11 and the substrate 110 are inclined by angle θ with respect to the liquid level (step S4). By inclining the anode holder 11, air (bubbles) can be suppressed from being trapped upon immersion. The first electrolyte circulates between the anodization tank 10 and the first electrolyte supply system 13.

The anode holder driving mechanism 12 then starts rotating the anode holder 11 (step S5). The anode holder 11 is rotated in a state of being inclined by angle θ with respect to the liquid level. Furthermore, as long as the anode holder is rotated in a state of being inclined with respect to the liquid level, it does not have to be in the same inclination angle as that at the time of immersing.

The current source 17 supplies a current between the anode 112 and the cathode 102 (step S6). While the current source 17 supplies the current, the anodization process is executed. As a result, porous layer is created on the front surface of the substrate 110.

When the current source 17 stops supplying the current, the anode holder driving mechanism 12 stops rotating the anode holder 11 (step S7).

The anode holder driving mechanism 12 then takes the anode holder 11 out from the anodization tank 10 (step S8).

The second electrolyte supply system 16 stops supplying the second electrolyte to the anode holder 11 (step S9).

The substrate 110 is recovered from the anode holder (step S10).

1.3 Advantageous Effects of Present Embodiment

According to the configuration of the present embodiment, it is possible to provide an anodization apparatus which can form a porous film with excellent in-plane uniformity on a substrate surface. Such advantageous effects will be explained in detail.

For example, when an anodization process is performed and HF in an electrolyte reacts with a silicon substrate, the concentration of HF in the electrolyte decreases, and hydrogen gas or H₂SiF₆ (SiF₆ ²⁻ ion) is produced as a by-product. In some cases, this may cause the composition (ion concentration) of the electrolyte to change, and deteriorate the uniformity of the porous layer in the substrate surface or in each substrate. Furthermore, when the anodization process is performed, in some cases, a pair of positive and negative charged particles is formed on the substrate surface, causing an electric field double layer to occur side by side in layers, which delays the supply of ions to the substrate surface and the draining of the by-products.

In contrast, according to the configuration of the present embodiment, the anodization apparatus 1 can immerse the substrate 110 in a state where it is inclined with respect to the first electrolyte. Furthermore, the anodization apparatus 1 can execute the anodization process while rotating the substrate 110 in an inclined state. This allows the anodization apparatus 1 to suppress air (bubbles) from being trapped when immersing the substrate 110 in the first electrolyte. Furthermore, when performing the anodization process, the anodization apparatus 1 can efficiently drain the gas (for example, hydrogen) generated on the substrate surface or the by-product (for example, SiF₆ ²⁻) from the substrate surface. By rotating the substrate 110, the anodization apparatus 1 can also increase the flow rate of the first electrolyte on the substrate surface, and reduce the thickness of the electric field double layer formed near the front surface of the substrate 110. Therefore, the anodization apparatus 1 can improve the uniformity of the ion supplied to the substrate surface, and improve the in-plane uniformity of the formed porous layer (the film-thickness uniformity of the porous layer and in-plane uniformity of porosity).

Furthermore, according to the configuration of the present embodiment, when performing the anodization process, the anodization apparatus 1 can provide the diffusion plate 104 in parallel with the substrate 110 between the anode 112 and the cathode 102. This allows the uniformity of the current density in the plane of the substrate 110 to be improved. Therefore, the in-plane uniformity of the formed porous layer can be improved.

Furthermore, according to the configuration of the present embodiment, the anodization apparatus 1 has a first electrolyte supply system. Since this allows the concentration of the first electrolyte in the anodization tank 10 to be maintained at a certain level, the concentration of the first electrolyte can be suppressed from changing during the anodization process and in each of the substrates. Thus, the uniformity of film quality in a depth direction of the porous layer formed on the substrate 110, and the film quality uniformity between the substrates, can be improved.

Furthermore, according to the configuration of the present embodiment, the anodization apparatus 1 supplies the second electrolyte between the anode 112 and the substrate 110. It is thereby possible to prevent the anode 112 and the substrate 110 from coming into contact. Thus, it is possible to reduce metal contamination of the substrate 110 caused by the anode 112.

Furthermore, according to the configuration of the present embodiment, by supplying the second electrolyte between the anode 112 and the substrate 110, bad conduction caused by a warp, etc., in the anode 112 or the substrate 110 can be suppressed between the anode 112 and the substrate 110.

2. Second Embodiment

A second embodiment will now be described. In the second embodiment, a specific example of an anodization process system in which a plurality of anodization tanks 10 described in the first embodiment are provided will be described.

2.1 Configuration of Anodization Process System

An example of the anodization process system will be described with reference to FIG. 4. FIG. 4 is a plan view of a configuration of an anodization process system 300.

As shown in FIG. 4, the anodization process system 300 includes a process module 301, a transfer module 302, a load port 303, and a load module 304.

The process module 301 is a module for performing various processes on the substrate 110. In the example of FIG. 4, the process module 301 includes three anodization tanks 310 to 312 and two washing tanks 313 and 314. The anodization tanks 310 to 312 correspond to the anodization tank 10 described in the first embodiment. For example, each composition of a first electrolyte in the anodization tanks 310 to 312 may be different, and the anodization process can be executed under different conditions. The washing tanks 313 and 314 are used for pre-cleaning or post-cleaning of the anodization process. The washing tanks 313 and 314 may be, for example, a sheet-type spin washing apparatus. It should be noted that the configuration of the process module 301 is not limited to this. For example, process units that are different from the anodization tank and the washing tank may be provided. It should also be noted that the number of the anodization tanks and the washing tanks is optional.

The transfer module 302 is provided in the process module 301. The transfer module 302 includes a handler 320. The handler 320 is configured to be driven to carry the substrate 110 to each tank in the process module 301.

The load port 303, for example, opens and closes a front opening unified pod (FOUP) 330. The FOUP 330 is set on the load port 303. The FOUP 330 is a sealed container for carrying the substrates 110. The FOUP 330 is able to store a plurality of substrates 110. It should be noted that although the example of FIG. 4 shows a case in which four load ports 303 are provided, the number of load ports 303 may be at least one.

The load module 304 includes a handler 340. The handler 340 is configured to be driven to carry the substrate 110 between the FOUP 330 and the transfer module 302.

2.2 Advantageous Effects of Present Embodiment

The anodization apparatus described in the first embodiment can be adopted in the anodization process system of the present embodiment.

3. Modification

An anodization apparatus according to above embodiments includes: a first process tank (10) configured to perform an anodization process on a substrate; a holder (11) configured to hold the substrate; and a first electrolyte supply system (13) configured to supply a first electrolyte to the first process tank. The holder immerses the substrate in the first electrolyte in a state where the substrate is inclined with respect to a liquid level of the first electrolyte. The anodization process is executed in a state where the substrate is inclined with respect to the liquid level of the first electrolyte.

The embodiments are not limited to the above-described aspects, and various modifications may be adopted therein.

For example, the substrate may be a substrate for heterogeneous computing, a substrate for micro electro mechanical systems (MEMS), a semiconductor wafer for a three-dimensional integrated circuit, a biometric/medical substrate, or an optical waveguide substrate, etc.

The state of being “coupled” in the foregoing embodiments includes a state of being coupled with something else indirectly interposed.

The expression “approximately the same” or “parallel” in the foregoing embodiments includes errors to the extent that the formation of porous layers when the anodization process is performed is not affected.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be implemented in a variety of other forms. Furthermore, various omissions, substitutions, and changes in the form of the embodiments may be made without departing from the spirit of the inventions. 

What is claimed is:
 1. An anodization apparatus comprising: a first process tank configured to perform an anodization process on a substrate; a holder configured to hold the substrate; and a first electrolyte supply system configured to supply a first electrolyte to the first process tank, wherein the holder immerses the substrate in the first electrolyte in a state where the substrate is inclined with respect to a liquid level of the first electrolyte, and the anodization process is executed in a state where the substrate is inclined with respect to the liquid level of the first electrolyte.
 2. The anodization apparatus according to claim 1, wherein the holder is rotated when the anodization process is performed.
 3. The anodization apparatus according to claim 1, further comprising: an anode provided in the holder; a second process tank provided in the first process tank; a cathode provided in the second process tank; and a diffusion plate provided at one end of the second process tank.
 4. The anodization apparatus according to claim 3, wherein the diffusion plate is provided at the one end of the second process tank in a state where it is inclined with respect to a bottom surface of the first process tank.
 5. The anodization apparatus according to claim 3, wherein when the anodization process is performed, the substrate and the diffusion plate are provided in a state of being inclined with respect to a bottom surface of the first process tank.
 6. The anodization apparatus according to claim 3, wherein when the anodization process is performed, the substrate and the diffusion plate are provided in parallel.
 7. The anodization apparatus according to claim 3, wherein the first electrolyte is supplied from the first electrolyte supply system to the second process tank, and the first electrolyte in the second process tank is supplied to a front surface of the substrate via the diffusion plate.
 8. The anodization apparatus according to claim 3, further comprising: a filter provided between the cathode and the diffusion plate.
 9. The anodization apparatus according to claim 3, further comprising: a second electrolyte supply system configured to supply a second electrolyte between the anode and the substrate.
 10. The anodization apparatus according to claim 3, wherein when the anodization process is performed, the substrate and the anode are provided in parallel.
 11. The anodization apparatus according to claim 1, wherein the first electrolyte supply system includes: a mixing tank used for producing the first electrolyte; an ingredient supply unit that supplies ingredients of the first electrolyte to the mixing tank; and a pump that supplies the first electrolyte produced at the mixing tank to the first process tank.
 12. The anodization apparatus according to claim 11, wherein the first electrolyte supply system is configured to recover the first electrolyte from the first process tank, and the recovered first electrolyte is supplied to the mixing tank.
 13. An anodization method comprising: supplying a first electrolyte to a process tank; setting a substrate on a holder in a manner facing an anode provided in the holder; filling a second electrolyte between the anode and the substrate; immersing the substrate set on the holder in the first electrolyte in a state where the substrate is inclined with respect to a liquid level of the first electrolyte; and in a state where the substrate is inclined, applying a current between the anode and a cathode provided in the process tank.
 14. The anodization method according to claim 13, further comprising rotating the substrate and the holder in a state where the substrate is inclined. 